package com.hmdp.service.impl;


import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;


/**
 * <p>
 *  服务实现类
 * </p>
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private CacheClient cacheClient;

    @Override
    public Result queryById(Long id) {
        //缓存穿透
//        Shop shop=cacheClient.queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class,this::getById,CACHE_SHOP_TTL,TimeUnit.MINUTES);
        //互斥锁解决缓存击穿
        //Shop shop = queryWithMutex(id);

        //逻辑过期解决缓存击穿
        Shop shop = cacheClient.queryWithLogicalExpire(CACHE_SHOP_KEY, id, Shop.class,this::getById,CACHE_SHOP_TTL,TimeUnit.MINUTES);

        if (shop==null){
            return Result.fail("店铺不存在!");
        }
        //7.返回
        return Result.ok(shop);
    }

    /*private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    //逻辑过期解决缓存击穿
    public Shop queryWithLogicalExpire(Long id) {
        String key= CACHE_SHOP_KEY +id;
        //1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if(StrUtil.isBlank(shopJson)){
            //3.存在，直接返回
            return null;
        }
        //4. 命中，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop=  JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //5. 判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())){
            //5.1 未过期，直接返回店铺信息
            return shop;
        }
        //5.2 已过期，需要缓存重建

        //6. 缓存重建
        //6.1 获取互斥锁
        String lockKey=LOCK_SHOP_KEY+id;
        boolean isLock = tryLock(lockKey);
        //6.2 判断是否获取锁成功
        if (isLock) {
            //6.3 成功，开启独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    //重建缓存
                    this.saveShop2Redis(id,20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    //释放锁
                    unLock(lockKey);
                }
            });
        }

        //6.4 返回过期的商铺信息
        
        return shop;
    }

    //缓存击穿
    public Shop queryWithMutex(Long id) {
        String key= CACHE_SHOP_KEY +id;
        //1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if(StrUtil.isNotBlank(shopJson)){
            // 检查是否为空值缓存
            if ("null".equals(shopJson)) {
                return null;
            }
            //3.存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //4. 实现缓存重建
        //4.1 获取互斥锁
        String lockkey=LOCK_SHOP_KEY+id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockkey);
            //4.2 判断是否获取锁成功
            if (!isLock) {
                //4.3 失败，则休眠并重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            //4.4 成功，根据id查询数据库
            shop = getById(id);
            //模拟重建延时
            Thread.sleep(200);
            //5.不存在，返回错误
            if (shop==null){
                //将空值写入redis
                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
                //返回错误信息
                return null;
            }
            //6.存在，写入redis
            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            //7.释放互斥锁
            unLock(lockkey);
        }
        //8.返回
        return shop;
    }*/

    //缓存击穿
    /*public Shop queryWithPassThrough(Long id) {
        String key= CACHE_SHOP_KEY +id;
        //1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if(StrUtil.isNotBlank(shopJson)){
            // 检查是否为空值缓存
            if ("null".equals(shopJson)) {
                return null;
            }
            //3.存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //4.不存在，根据id查询数据库
        Shop shop = getById(id);
        //5.不存在，返回错误
        if (shop==null){
            //将空值写入redis
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
            //返回错误信息
            return null;
        }
        //6.存在，写入redis
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //7.返回
        return shop;
    }*/

/*
    //尝试获取锁
    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    //释放锁
    private void unLock(String key){
        stringRedisTemplate.delete(key);
    }

    //逻辑过期
    public void saveShop2Redis(Long id, Long expireSeconds) throws InterruptedException {
        //1.查询店铺数据
        Shop shop = getById(id);
        Thread.sleep(200);
        //2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3.写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(redisData));
    }*/

    /**
     * 更新商铺信息
     * @param shop 商铺数据
     * @return 无
     */
    @Transactional
    public Result update(Shop shop) {
        Long id=shop.getId();
        if(id==null){
            return Result.fail("店铺id不能为空");
        }
        //1.更新数据库
        updateById(shop);
        //2.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY+id);
        return Result.ok();
    }
}
